The hidden buttons are used for network administrator functions, to add the minimote to the network, to associate zwave devices, etc. they can’t be used for anything else as far as I know.
As far as a regular wall panel, there are a couple of topics in the UK section of the forum where people have looked at some UK frequency devices, but I don’t know if anyone ever got them working.
I myself can’t physically work a minimote, I don’t have enough hand function, but we do own one that my housemate uses. The buttons are a little bit recessed so we haven’t had any problems with them being accidentally pressed. Even if you flip the minimote over upside down on the table the buttons don’t get pressed.
@tgauchat has done a lot with minimotes, so would probably know more.